Illuminators for knitting machines



Jan. 21, 1958 c. o. MEINERS ETAL 2,820,356

ILLUMINATORS FOR KNITTING rvmcmmras Filed July 2. 1956 tlomeyg ILLUMINATORS FOR KNITTING MACHINES Carl Otto Meiners, Stuttgart, Germany, and Heinz Walter Lessing and Walter Benno Lessing, London, England, assignors to Meiners Optical Devices Limited, London, England Application July 2, 1956, Serial No. 595,415

Claims priority, application Great Britain July 7, 1955 5 Claims. (Cl. 66-86) This invention relates to knitting machines.

The piecing-up of a broken thread in a fiat bar knitting machine can be a troublesome operation mainly because of the difficulty of locating the ends to be pieced. This casts shadows and the quality of the light is such that even if the light can be suitably directed, it illuminates everything in its path to the same extent.

The problem has been solved in spinning frames by the use of an illuminator which illuminates the yarns which leave the drawing rollers.

The present invention is concerned with the equivalent problem in flat bar knitting machines, i. e. warp, fiat weft, Raschel and lace-lever machines.

Experiments which we have made show that the approach which has to be made in kniting machines is quite dilferent from that which has to be made in spinning machines. Whereas in the latter machines, success can be achieved by suitably illuminating the threads, we have found that success is best achieved in knitting machines by suitably illuminating principally the knitted fabric as it emerges from the machine. The present invention is based on that discovery.

According to the invention, a flat bar knitting machine is provided with an illuminator comprising a lens system which directs on the fabric as it emerges from the machine a substantially parallel beam of light of short wave length lying not substantially beyond the blue and bluegreen ranges of the spectrum.

The illumination of the fabric which is obtained in that manner enables breaks to be detected quite rapidly, the detection being indirect in that what is made visible is the effect of a break rather than the break itself. The fault in the cloth is shown in bold relief and the operators attention is drawn to it and consequently to the break which has caused it even if he is at some distance from the point at which the break has occurred.

The ease with which the existence of a fault can be detected if the cloth is illuminated as is proposed in accordance with the invention is quite remarkable and enables the operator to stop the machine promptly and re-thread a broken thread at a very early stage.

In the preferred embodiment of the invention, the illuminator is mounted at the side of the machine to project the beam along the lines of the needle ends, that is to say along the length of the machine to illuminate the fabric as it emerges from the machine, the needles themselves, and the places where the ends of a broken thread are often to be found.

The light emitted by the source has short waves extending not substantially beyond the blue or blue-green United States Patent F 2,820,356 Patented Jan. 21, 1958 range of the spectrum. This, it is found, serves to bring the fabric and thread ends into special prominence no matter what is the background against which they are viewed. Light of that quality can be obtained, for example, from a mercury vapour discharge lamp.

The degree of illumination should be fairly high. A stilb value of about 1,000 is adequate. The stilb is a unit of brightness equal to that of aluminous surface having an intensity of one candle per sq. cm. of projected area. (Authority, British Standard specification 205:1943.

The best cross-section of the beam varies from machine to machine, depending among other things on the relative directions of the warps proceeding towards the needles and of the knitted fabric proceeding away from the needles. A beam of oval cross-section is very useful which is set so that the longer axis of the oval is parallel to the plane of the fabric.

It is also advantageous to have the illuminator mounted so that it can be set in different angular positions to suit any particular machine. Also, such adjustability enables the illuminating beam to be directed more particularly on to the cloth or the needles according to the needs of the moment.

In order that the invention may be clearly understood, reference is made by way of example to the accompanying diagrammatic drawings, in which:

Figure l is a perspective view showing an illuminator according to the invention and portion of a flat bar knitting machine;

Figure 2 is a side elevation of the arrangement in Figure 1; and

Figure 3 is a perspective view of the illuminator shown in Figure 1.

Referring to the drawings, an illuminator 18 is mounted at the side of a flat bar knitting machine so that it projects a light beam 2 along the lines of the needle ends 3 and 4, i. e. along the length of the machine. The cross-section of the beam is circular.

Figure 2 illustrates knitted fabric 5 emerging from the machine and being illuminated in the region of the needle ends, thus enabling a break to be detected indirectly by showing a fault in the fabric 5 in bold relief.

In addition, illumination of the needle ends 3 and 4 facilitates the detection and replacement of a broken needle before the fault in the fabric caused by a broken needle becomes extensive. Further, since the ends of a broken thread are often to be found in the vicinity of the needle ends, direction of the beam as indicated in Figures 1 and 2 has proved to be most advantageous.

The illuminator 18 is shown separately in Figure 3. It comprises a casing providing a housing 20 for a lamp 22 and a trunk 24. Within the trunk there is an apertured plate 26 forming an optical stop and a plane mirror 28 which is set at 45 to the axis of the trunk. In one face of the trunk there is a lens 30 which collects the light reflected by the mirror 28.

The lamp 22 is a mercury vapour lamp, and can have a brightness of approximately 1000 stilb. By virtue of the optical system of the illuminator, it projects along the machine a slightly convergent beam. The optical system could, however, be other than that specifically illustrated. For example, instead of the lens 30 receiving from the lamp 22 a divergent beam via the mirror 28 to transmit it as a slightly convergent beam, the mirror could be omitted and the lens 30 located in the end of the trunk 24 in axial alignment with the apertured plate 26. Alternatively, the lens 30 could be located intermediate the ends of the trunk 24 to receive the incident beam directly, the emergent beam then being reflected by a mirror to emerge at right angles to the trunk.

than it had on leaving the lens.

A collector lens maybe included in the optical system immediately-beyond the stop 26.

In all cases the lens 30 is designed to produce a convergent beam the point of convergence of which is at 'least halfway along the length of the machine so that at the far end'it'will not have diverged togreater dimensions A beam of restricted dimensions becomes acceptable because of the high degree of brightness of the source and has the advantage of illuminating substantially only the parts to be illuminated,

'as' shown in Figure 2.

Since the convergence is only slight, the beam is to all intents and purposes parallel over the length of the ma- 'chine.

We claim:

1. In a flat bar knitting machine, rows of needles along the length of the machine for knitting fabric and an illuminator mounted at the side of the machine comprising a housing for a lamp which emits light of short wave length lying not substantially beyond the blue and bluegreen range of the spectrum and a lens system within said housing, the said lens system being adapted to receive light from the said lamp and direct it as a substantially parallel beam along the lines of the needle ends, whereby to illuminate the needles and the fabric knitted thereby.

2. In a flat bar knitting machine, rows of needles along the length of the machine for knitting fabric and an illuminator mounted at the side of the machine comprising a housing for a lamp which emits light of short wave length lying not substantially beyond theblue and bluegreen range of the spectrum and a lens system within said 4 housing, the said lens system being adapted to receive light from the said lamp and direct it as a substantially parallel beam of oval cross-section along the lines of the needle ends, whereby to illuminate the needles and the fabric knitted thereby, the longer axis of the oval being set parallel to the plane of the knitted fabric.

3. In a flat bar knitting machine, the combination according to claim 1 in which the said lamp is of the mercury vapour discharge type having a brightness of approximately 1000 stilb.

4. In a flat bar knitting machine, the combination according to claim 2 in which the said lamp is of the mercury vapour discharge type having a brightness of approximately 1000 stilb.

5. In a .flat bar knitting machine, an illuminator comprising a housing for a lamp which emits light of short wave length lying not substantially beyond the blue and blue-green range of the spectrum and a lens system within saidthousing, the said lens system being adapted to receive light from the said lamp and direct it as a slightly convergent beam onto knitted fabric as it emerges from the machine, and the point of convergence of the said beam being at least halfway along the length of the machine.

References Cited in the file of this patent UNITED STATES PATENTS 1,930,077 Bentley Oct. 10, 1933 2,166,851 Verbeek July 18, 1939 2,169,272 Miller Aug. 15, 1939 2,421,092 Thomas May 27, 1947 

